Polyacrylonitrile-based carbon fiber brush (PAN-CFB) cathode was used to electrogenerate hydrogen peroxide (H2O2) via oxygen reduction reaction (ORR) and to degrade phenol in electro-Fenton system. Due to inherent N-containing structure, PAN-CFB cathode generated H2O2 efficiently (current efficiency at 300 mA >90%), showing high selectivity toward 2-electron ORR independent of medium (H2SO4, Na2SO4 or NaOH). Moreover, the influence of parameters such as applied current, cathodic potential, electrolyte concentration and volume as well as electrode distance on H2O2 electrogeneration was investigated in detail. Finally, the degradation of phenol was evaluated by ultraviolet (UV) spectra analysis and COD measurement. 86.2% of COD removal was achieved under the optimum conditions (pH 3, I = 300 mA, 0.3 mmol L-1 Fe2+) after 240 min, meaning the almost complete degradation of phenol via electro-Fenton process using PAN-CFB cathode. (C) 2015 Elsevier Ltd. All rights reserved.